Accumulated thermal effect (ATE), which can be an artifact in femtosecond closed-aperture Z-scan measurements, was investigated by varying the repetition rate of the incident pulse for a dye solution in CHCl3. It was found that the measurement is affected by two-photon-absorption-induced ATE, even at a low repetition rate of 1 kHz. The relaxation time of the ATE was found to be tens of milliseconds by time-resolved thermal-lens experiments and simulations, which is consistent with the observed repetition-rate dependence of the Z-scan measurements. The simulations for various commonly used solvents also exhibited that the ATE can be prominent in hydrocarbon and halogenated hydrocarbon solvents and inconspicuous in alcohols and water.
© 2003 Optical Society of America
(190.4180) Nonlinear optics : Multiphoton processes
(190.4710) Nonlinear optics : Optical nonlinearities in organic materials
(190.4870) Nonlinear optics : Photothermal effects
(190.5940) Nonlinear optics : Self-action effects
(190.7110) Nonlinear optics : Ultrafast nonlinear optics
Kenji Kamada, Kinu Matsunaga, Akihiro Yoshino, and Koji Ohta, "Two-photon-absorption-induced accumulated thermal effect on femtosecond Z-scan experiments studied with time-resolved thermal-lens spectrometry and its simulation," J. Opt. Soc. Am. B 20, 529-537 (2003)